Carbocyanine dyes and process of manufacturing the same



Patented July 13, 1937 CARBOCYANINE EYES AND PROCESS OF MANUFAGTUEING THE SAME Walter Zeh, Dessau in Anhalt, Germany, assignor to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York No Drawing. Application February 6, 1932, Se-

rial No. 591,389.

3 Claims.

My present invention relates to sensitizing of photographic emulsions.

One of its objects is to provide such an emulsion the sensitivity of which is raised over the 5 range of wave lengths to which the emulsion is normally sensitive. Another object is the dyes incorporated in the emulsion, in order to increase their sensitivity. Further objects will be seen from the detailed specification following here- 10 after.

I have found that a silver-halide emulsion containing a dye of the general formula 20 V=H, alkyl, alkoxy, substituted amino groups,

halide, B=I-I, alkyl, r=alkyl, 25 X=halide, perchlorate, 'paratoluene sulfonate,

alkylosulfate, nitrate, is sensitive to wave lengths extending from the green to the red region of the spectrum. The emulsion attains a remarkable sensitivity to the 30 gggge of wave lengths from about 500 to about M- In general Formula 1 V may take any position in the benzene nuclei, however, the 5 and 6 position and the 5' and 6' position are preferred. 5 V may represent alkyl, such as methyl, ethyl, etc. or an alkoxy, for instance, a methoxy or an ethoxy group, or halide, or an amino group both hydrogen atoms of which-are replaced by alkyl or one of the hydrogen atoms being replaced by alkyl and the other by aryl, and finally one of the hydrogen atoms being replaced by an acyl radical. B may be H or alkyl such as methyl, ethyl, etc. 1 may represent alkyl, for instance, methyl or ethyl. X can be any suitable anion that will precipitate the dye, for instance, a halide, paratoluene sulfonate, alkylsulfate, perchlorate, nitrate, or the like.

The dyes are obtainable according to the desired solubility in form of the bromide, iodide, 50 perchlorate, etc. and are used in a quantity as usual for the known sensitizing dyes. This quantity amounts for the trimethinecyanines which are not substituted in the carbon bridge to about 10 to 20 milligrams per 1 kg. of emulsion ready In Germany February 7, 1931 which are substituted in the carbon bridge and those which are not substituted in the carbon bridge.

suitable amount will in. each'case be found by a few comparative experiments. The dyes may be added to the emulsion in form of solutions. Suitable solvents are the alcohols, for instance, methyl or ethyl alcohol which may be used anhydrous or diluted with water. The dyes are applied to the emulsion during any stage of its production, however, they arepreferably added to the finished emulsion before being cast. The dyes may likewise be added by coating the emulsion with them or by bathing the finished photographic material in a bath in which the dye is dissolved. The dyes are suited for sensitizing an emulsion made according to the boiling process as well as for sensitizing an emulsion made according to the ammonia process.

The following examples serve to illustrate my invention.

Example 1.-The dye bis-[3-ethyl-5-methylbenzselenazole (2)] trimethinecyanine corresponding to the formula is obtainable as follows:

A solution of 5.5 grams of 2.5-dimethyl-benz- I l-Iowever I do not wish to limit my in vention to the quantities just indicated, the most iodide ozH a \I 02115 8 grams of 2-methyl-5-ethoxy-benzselenazoleethyl-iodide in 40 cc. of pyridine are boiled with 8 cc. of ethyl ortho-formate for about /2 hour. The dye separates in form of green needles. After cooling the dye is filtered eventually after addition of a small quantity of an aqueous solution of potassium iodide. Recrystallized from methanol the dye is obtainable in form of green little rods.

The alcoholic solution of the dye has an absorption maximum at a wave length of about 597/1./.L.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitivity from about 505 to about GQG/LM with a maximum at about 628 141" Example 3.The dye bis-[3-ethyl-6-methoxybenzselenazole (2) l trimethinecyanine iodide corresponding to the formula moo- S8 Se 7 6 OOHa 1 H H H 1 r t A nuts. J f' Ga \I (32115 is produced by boiling 4 grams of Z-methyl-G- methoXy-benzselenazole-ethyl-iodide dissolved in 20 cc. of pyridine with 4 cc. of ethyl orthoformate for about /2 hour and precipitating the formed dye by addition of a small quantity of an aqueous solution of potassium iodide of 5 per cent strength. After recrystallization from methanol a blue crystal powder is obtainable.

The alcoholic solution of the dye has an absorption maximum at a wave length of about 595mb.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitivity from about 505 to about 690 with a maximum at about 625m.

Example 4.-Ther dye bis-[3-ethyl-5-chlorobenzselenazole (2)] trimethinecyanine iodide corresponding to the formula ethyl-benzselenazole- 2) l fi-methyl-trimethinecyanine bromide corresponding to the formula 10 grams of 2-methyl-benzselenazole-dimethylsulfate in 20 cc. of pyridine are boiled with 10 cc. of ethyl ortho-acetate for about 2 hours.

After cooling the mixture, the dye is precipitated by addition of about to cc. of an aqueous solution of potassium bromide. By recrystallization from methanol the dye is obtainable in form of a dark carmine red crystal powder.

The alcohclic solution of the dye has an absorption maximum at a wave length of about 5551.011.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitivity from about 490 to about 690 with a maximum at about 605,141..

Example 6.-For producing the dye bis-[3- ethyl 6 acetylamino-benzselenazole 2)] (3 methyl-trimethinecyanine bromide corresponding to the formula Incorporated in a silver-halide emulsion the 'dye imparts to it a range of sensitivity from about 490 to about 700 with a maximum at Example 7. The dye bis-[3-methyl-benzselenazole- (2) l ,8 ethyl-trimethinecyanine bromide corresponding to the formula is obtainable by boiling for about /2 hour a mixture of 5 grams of 2-methyl-benzselenazole-dimethylsulfate, 10 cc. of pyridine and 5 cc. of

ethyl ortho-propionic acid. After the addition of an aqueous solution of potassium bromide of about 5 per cent strength the dye precipitates from the dark bluish red solution in form of brownish red flakes.

The alcoholic solution of the dye has an absorption maximum at a wave length of about 560/144.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitivity from about 500 to about 700 with a maximum at about 655 Example 8.-The dye bis-[3-ethyl-5-methoxybenzselenazole- (2)] p ethyl-trimethinecyanine perchlorate corresponding to the formula Se 1 1 5 2 H300 4 2 C O Se- F l 2 2 15 0104 02115 may be obtained by boiling for about hour a mixture of 4 grams of 2-methy1-5-metho-xybenzselenazole-diethylsulfate, 10 cc. of pyridine and 4 cc. of ethyl ortho-propionate, and precipitating the dye by addition of a small quantity of an aqueous solution of sodium perchlorate of about 5 per cent strength. Recrystallization from methanol yields small green needles.

The alcoholic solution of the dye has an absorption maximum at a wave length of about 573/.t/L.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitivity from about 490 to about 720IL/L with a maximum at about 658 Example 9.For producing the dye bis-[3- methyl 6 propionylamino-benzselenazole- (2) p-ethyl-trimethinecyanine bromide corresponding to the formula and may by recrystallization be obtained in form of a greenish red crystal powder.

The alcoholic solution of the dye has an absorption maximum at a wave length of about 575,440.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitivity from about 490M, to about 710 with a maximum at about 590/L,LL.

The bases serving as a starting material for the production of the dyes are obtainable according to methods known from the preparation of the unsubstituted benzselenazoles.

It is to be understood that my invention is not limited to the foregoing examples nor to the specific details given therein. Numerous other embodiments are possible and I contemplate as included within my invention all such modifications and equivalents as fall within the scope of the appended claims. So, for instance, the benzene nuclei may contain one or more substituents.

What I claim is:

1. A bis-[3-alkyl 5 alkoxy benzselenazole- (2) l -trimethinecyanine salt, the central carbon of the trimethenyl chain of which is substituted by a member selected from the group consisting of hydrogen and alkyl.

2. A bis-[3-alkyl 5 methoxy-benzselenazole- 4 grams of 2-methyl-fi-propionylamino-benzselenazole-dimethylsulfate in 20 cc. of pyridine are boiled for about hour with 4 cc. of ethyl orthopropionate. After the addition of a small quantity of an aqueous solution of potassium bromide 40 of about 5 per cent strength the dye precipitates (2) l-,B-ethyl-trimethinecyanine salt.

3. Bis [3-ethyl 5 methoxy-benzselenazole- (2) l-p-ethyl-trimethinecyanine perchlorate.

WALTER ZEH. 

